CN114174684A

CN114174684A - Multistage rotary compressor and refrigeration cycle device

Info

Publication number: CN114174684A
Application number: CN201980098795.5A
Authority: CN
Inventors: 平山卓也; 知念武士; 木村茂喜
Original assignee: Toshiba Carrier Corp
Current assignee: Toshiba Carrier Corp
Priority date: 2019-08-21
Filing date: 2019-08-21
Publication date: 2022-03-11
Anticipated expiration: 2039-08-21
Also published as: WO2021033283A1; CN114174684B; CN116378957A; JP7195446B2; JPWO2021033283A1

Abstract

The present invention relates to a multistage rotary compressor and a refrigeration cycle device. The multistage rotary compressor of the embodiment includes a rotary shaft, a driving element provided on one axial end side of the rotary shaft, and a compression element provided on the other axial end side of the rotary shaft, inside a casing. The compression element includes a low-stage compression mechanism section for compressing a low-pressure working fluid to an intermediate pressure, a high-stage compression mechanism section for compressing a high-pressure working fluid to an intermediate pressure, and a partition plate for partitioning the two compression mechanism sections. The compression mechanism units have a1 st bearing and a 2 nd bearing on the opposite side of the partition plate, respectively. The partition plate is provided with an intermediate-pressure space for discharging the working fluid of intermediate pressure compressed by the low-stage compression mechanism. The partition plate is provided with a low-stage discharge hole and a low-stage side discharge valve device. The 2 nd bearing on the high stage compression mechanism side is provided with a high stage discharge hole and a high stage side discharge valve device. The thickness of the portion of the partition plate where the low stage valve seat is formed is smaller than the thickness of the portion of the 2 nd bearing where the high stage valve seat is formed.

Description

Multistage rotary compressor and refrigeration cycle device

Technical Field

Embodiments of the present invention relate to a multistage rotary compressor and a refrigeration cycle apparatus.

Background

Conventionally, a multistage rotary compressor is known which compresses a working fluid in stages by rotation of an eccentric portion. For example, the multistage rotary compressor includes a low-stage compression mechanism section that compresses a low-pressure working fluid to an intermediate pressure, and a high-stage compression mechanism section that compresses the intermediate-pressure working fluid compressed by the low-stage compression mechanism section to a high pressure. The multistage rotary compressor includes a hermetic casing that houses a compression element and a drive element. The high-pressure working fluid compressed by the high-stage compression mechanism is discharged into the sealed housing.

In some multistage rotary compressors, a low-stage discharge port and a discharge valve device are provided in a partition plate, and a high-stage discharge port and a discharge valve device are provided in a high-stage bearing. An intermediate pressure space is provided inside the partition plate. In order to suppress pulsation of the intermediate-pressure working fluid discharged from the low-stage compression mechanism, it is desirable to ensure a large intermediate-pressure space. For this reason, it may be considered to increase the thickness of the partition plate. However, when the thickness of the partition plate is simply increased, the distance between the two bearings on the low stage side and the high stage side is increased, and the deflection of the rotary shaft is easily generated.

Further, it is conceivable to increase the sealing area between the roller end surface and the partition plate by reducing the inner diameter of the through hole in the partition plate through which the rotating shaft is inserted. The efficiency of the multistage rotary compressor is improved by securing the above-mentioned sealing area to improve the airtightness of the compression chamber. However, in order to secure the above-described seal area, it is necessary to reconsider the dimensional relationship between the eccentric portion of the rotary shaft and the roller.

In addition, there is also an example in which the working fluid discharged to the intermediate pressure space is discharged to the inside of the housing via the muffler space. In this case, the compressed fluid having a high temperature and a high pressure may be discharged into the casing without being sufficiently cooled. This may cause overheating of the electric motor, a reduction in motor efficiency, demagnetization of the magnet, and the like.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 6176782

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing a multistage rotary compressor and a refrigeration cycle device that can ensure an intermediate pressure space formed in a partition plate, ensure a sealing area of a roller end surface, and improve the cooling performance of a discharge fluid.

Means for solving the problems

The multistage rotary compressor according to the embodiment includes a rotary shaft, a driving element provided on one axial end side of the rotary shaft, and a compression element provided on the other axial end side of the rotary shaft, in a casing. The compression element includes a low-stage compression mechanism section for compressing a low-pressure working fluid to an intermediate pressure, a high-stage compression mechanism section for compressing a high-pressure working fluid to an intermediate pressure, and a partition plate for partitioning between the two compression mechanism sections. The compression mechanism units have a1 st bearing and a 2 nd bearing on the opposite side of the partition plate, respectively. The partition plate is provided with an intermediate-pressure space into which the intermediate-pressure working fluid compressed by the low-stage compression mechanism section is discharged. The partition plate is provided with a low-stage discharge hole and a low-stage side discharge valve device. The 2 nd bearing on the high stage compression mechanism side is provided with a high stage discharge hole and a high stage side discharge valve device. The thickness of the portion of the partition plate where the low stage valve seat is formed is smaller than the thickness of the portion of the 2 nd bearing where the high stage valve seat is formed.

Drawings

Fig. 1 is a schematic configuration diagram of a refrigeration cycle apparatus including a sectional view of a multistage rotary compressor according to an embodiment.

Fig. 2 is a sectional view of a compression element of the multistage rotary compressor according to the embodiment.

Fig. 3 is a sectional view III-III of fig. 2.

Fig. 4 is an explanatory diagram showing the order of assembling the low-stage side roller to the rotary shaft of the multistage rotary compressor according to the embodiment in the order of (a) to (d).

Fig. 5 is an enlarged view of a main portion of fig. 1.

Detailed Description

Hereinafter, a multistage rotary compressor and a refrigeration cycle apparatus according to an embodiment will be described with reference to the drawings.

First, a refrigeration cycle apparatus will be described.

Fig. 1 is a schematic configuration diagram of a refrigeration cycle apparatus including a sectional view of a multistage rotary compressor according to an embodiment. The refrigeration cycle apparatus 1 of the embodiment includes: a multistage rotary compressor 2 having a compressor main body 11 and an accumulator (gas-liquid separator) 12, and compressing a gas refrigerant as a working fluid; a radiator 3 connected to the discharge portion 15 of the compressor body 11 and cooling the high-temperature and high-pressure gas refrigerant discharged from the compressor body 11; an expansion device (expansion valve) 4 connected to the downstream side of the radiator 3 and configured to decompress the refrigerant; and an evaporator (heat absorber) 5 connected between the expansion device 4 and the introduction portion 12a of the accumulator 12, and evaporating the refrigerant. In the figure, reference numeral 13 denotes an introduction passage extending from the discharge portion 15 of the compressor main body 11 to the introduction portion 12a of the accumulator 12.

The lead-out portion 12b of the accumulator 12 and the suction portion 14 of the compressor main body 11 are connected by the suction pipe 6. The gas refrigerant, which has been gas-liquid separated in the accumulator 12, is guided to a low-stage compression mechanism 37 of the compressor main body 11, which will be described later, via the suction pipe 6.

The refrigeration cycle apparatus 1 shown in fig. 1 includes an intermediate pressure passage 7, and the intermediate pressure passage 7 guides an intermediate-pressure gas refrigerant compressed by the low-stage compression mechanism 37 of the compressor main body 11 to the intercooler 7 a. The intermediate pressure passage 7 guides the intermediate-pressure gas refrigerant compressed by the low-stage compression mechanism 37 of the compressor body 11 to the high-stage compression mechanism 38 of the compressor body 11. The intermediate pressure passage 7 extends from the 2 nd discharge portion 15a communicating with the low stage compression mechanism portion 37 to the 2 nd suction portion 14a communicating with the high stage compression mechanism portion 38.

The refrigeration cycle apparatus 1 includes a 2 nd accumulator (gas-liquid separator) 8 and a 2 nd expansion device (expansion valve) 9 between the expansion device 4 and the evaporator 5. A bypass passage 8a for guiding the gas refrigerant gas-liquid separated in the 2 nd accumulator 8 to the high-stage compression mechanism unit 38 is provided between the 2 nd accumulator 8 and the 2 nd suction portion 14a of the high-stage compression mechanism unit 38 of the compressor main body 11. The bypass passages 8a in fig. 1 join together in the middle of the intermediate pressure passage 7.

The pressure of the gas refrigerant gas-liquid separated in the 2 nd accumulator 8 is equal to the intermediate pressure of the gas refrigerant compressed by the low-stage compression mechanism 37 of the compressor main body 11. Further, the intermediate pressure passage 7, the bypass passage 8a, the 2 nd accumulator 8, and the 2 nd expansion device 9 may be eliminated.

The multistage rotary compressor 2 is a so-called rotary compressor. The multistage rotary compressor 2 compresses a low-pressure gas refrigerant taken into the interior thereof in two stages to obtain a high-temperature high-pressure gas refrigerant. The specific configuration of the multistage rotary compressor 2 will be described later.

The refrigerant as the working fluid circulates in the refrigeration cycle apparatus 1 while changing phase into a gas refrigerant and a liquid refrigerant. The refrigerant absorbs heat during a phase change from a liquid refrigerant to a gaseous refrigerant. The heat absorption is utilized to perform freezing, refrigeration, and the like. For example, HFC refrigerants such as R410A and R32, HFO refrigerants such as R1234yf and R1234ze, and natural refrigerants such as CO2 can be used as the refrigerant.

The radiator 3 radiates heat from the high-temperature and high-pressure gas refrigerant sent from the multistage rotary compressor 2.

The expansion device 4 reduces the pressure of the high-pressure refrigerant sent from the radiator 3 to turn the refrigerant into a low-temperature low-pressure liquid refrigerant.

The evaporator 5 vaporizes the low-temperature low-pressure liquid refrigerant sent from the expansion device 4 into a low-pressure gas refrigerant. In the evaporator 5, the low-pressure liquid refrigerant takes vaporization heat from the surroundings at the time of vaporization, and the surroundings are cooled. The low-pressure gas refrigerant having passed through the evaporator 5 is taken into the multistage rotary compressor 2.

In the refrigeration cycle apparatus 1, the intermediate-pressure gas refrigerant gas-liquid-separated in the 2 nd accumulator 8 is introduced into the high-stage compression mechanism 38 of the compressor main body 11 through the bypass passage 8 a. This improves the compression performance of the compressor body 11.

Next, the multistage rotary compressor 2 will be described.

As shown in fig. 1, the multistage rotary compressor 2 according to the embodiment includes a compressor main body 11 and an accumulator 12.

The accumulator 12 is a so-called gas-liquid separator. The accumulator 12 is provided between the evaporator 5 and the compressor body 11. The accumulator 12 is connected to the compressor main body 11 through the suction pipe 6. The accumulator 12 supplies only the gas refrigerant of the gas refrigerant vaporized in the evaporator 5 and the liquid refrigerant not vaporized in the evaporator 5 to the compressor body 11.

The compressor body 11 includes a rotary shaft 31, an electric motor (driving element) 32, a compression element 33, and a sealed casing 34 that houses the rotary shaft 31, the electric motor 32, and the compression element 33. The compressor body 11 is disposed such that the axial directions of the rotary shaft 31 and the sealed housing 34 are vertical. The rotary shaft 31 has a rotation center axis C coincident with a center axis of the hermetic case 34. In the following description, a direction along the central axis C of the rotary shaft 31 and the sealed housing 34 is simply referred to as an axial direction, a direction perpendicular to the axial direction is referred to as a radial direction, and a direction around the central axis C is referred to as a circumferential direction.

Both axial ends of the cylindrical body of the sealed case 34 are closed to form a sealed container. In the sealed case 34, an electric motor 32 is housed on the upper side, and a compression element 33 is housed on the lower side. These electric motors 32 and compression elements 33 are coupled via a rotating shaft 31. In the sealed housing 34, an electric motor 32 is provided on one end side of the rotary shaft 31, and a compression element 33 is provided on the other end side of the rotary shaft 31. An annular frame 34a fixed to the inner wall surface of the sealed case 34 is provided between the electric motor 32 and the compression element 33 in the sealed case 34.

A lubricant J for lubricating the compression element 33 is stored in the bottom of the closed casing 34. The bottom of the sealed case 34 constitutes a lubricant oil reservoir 34b that stores lubricant oil J. A part of the compression element 33 is immersed in the lubricating oil J. In the sealed casing 34, the high-pressure gas refrigerant compressed by the high-stage compression mechanism 38 is discharged into a space in the sealed casing 34.

The electric motor 32 is a so-called inner rotor type DC brushless motor. The electric motor 32 is an electric motor including a stator 35 and a rotor 36. The stator 35 is fixed to an inner wall surface of an upper portion of the hermetic case 34. The rotor 36 is disposed inside the stator 35 at a radial interval and fixed to an upper portion of the rotary shaft 31.

Fig. 2 is a sectional view of the compression element 33 of the multistage rotary compressor 2. Fig. 3 is a sectional view III-III of fig. 2.

As shown in fig. 2 and 3, the compression element 33 is a multi-cylinder compression element having a plurality of

cylinders

37a and 38 a. For example, the compression element 33 is a double-cylinder (multi-cylinder) compression element having a pair (a plurality of)

cylinders

37a and 38a arranged in the axial direction. The compression element 33 of the embodiment includes a low-stage compression mechanism 37 located on the upper side in the axial direction (on the electric motor 32 side), a high-stage compression mechanism 38 located on the lower side in the axial direction (on the opposite side to the electric motor 32), and a partition plate 39 partitioning between the low-stage compression mechanism 37 and the high-stage compression mechanism 38 in the vertical direction (axial direction). The low-stage compression mechanism 37 compresses (boosts) the low-pressure working fluid drawn from the accumulator 12 to an intermediate pressure. The high-stage compression mechanism unit 38 compresses (boosts) the intermediate-pressure working fluid compressed by the low-stage compression mechanism unit 37 to a high pressure.

The low-stage compression mechanism 37 includes a low-stage side cylinder 37a, and the low-stage side cylinder 37a is provided so as to be axially parallel to the rotary shaft 31 and to vertically penetrate the rotary shaft 31. The low-stage cylinder 37a is formed with a circular low-stage cylinder hole 37b having a center axis coincident with the rotation center axis C of the rotary shaft 31. The low-stage compression mechanism 37 includes a1 st bearing 41 on the upper side of the low-stage cylinder 37a (on the opposite side of the partition plate 39 in the axial direction), and the 1 st bearing 41 blocks the upper end opening of the low-stage cylinder hole 37b and rotatably supports the 1 st main shaft 31a on the upper side of the rotary shaft 31.

The high-stage compression mechanism 38 includes a high-stage cylinder 38a, and the high-stage cylinder 38a is provided so as to be axially parallel to the rotary shaft 31 and so as to vertically penetrate the rotary shaft 31. The high-stage cylinder 38a is formed with a circular high-stage cylinder hole 38b having a center axis coincident with the rotation center axis C of the rotary shaft 31. That is, the high-stage cylinder hole 38b and the low-stage cylinder hole 37b are disposed coaxially with each other and the rotary shaft 31. The high-stage compression mechanism 38 includes a 2 nd bearing 42 on the lower side of the high-stage cylinder 38a (on the opposite side of the partition plate 39 in the axial direction), and the 2 nd bearing 42 blocks the lower end opening of the high-stage cylinder hole 38b and rotatably supports the 3 rd main shaft 31e on the lower side of the rotary shaft 31.

The outer peripheral portion of the low-stage side cylinder 37a is fastened and fixed to the frame 34a by a bolt B1 inserted from below in a state of being in contact with the lower surface of the frame 34 a. The 1 st bearing 41 is disposed on the inner peripheral side of the frame 34 a. The 1 st bearing 41 is fastened and fixed to the low-stage side cylinder 37a by a bolt B2 inserted from above in a state of being in contact with the upper surface of the low-stage side cylinder 37 a. The bolt B2 passes through the low-stage cylinder 37a, extends downward, further passes through the partition plate 39 and the high-stage cylinder 38a, and is then screwed into and fastened to a screw hole of the 2 nd bearing 42. Thereby, the 1 st bearing 41, the low-stage side cylinder 37a, the partition plate 39, the high-stage side cylinder 38a, and the 2 nd bearing 42 are integrally fastened in a stacked state, and the stacked body thereof is fixed to the frame 34 a. The rotary shaft 31 is rotatably supported by a1 st bearing 41 and a 2 nd bearing 42 fixed to the frame 34a and further to the hermetic case 34.

The upper end opening of the lower stage cylinder hole 37b of the lower stage cylinder 37a is closed by the 1 st bearing 41, and the lower end opening of the lower stage cylinder hole 37b is closed by the partition plate 39. A space defined by the low-stage cylinder 37a, the 1 st bearing 41, and the partition plate 39 is a low-stage cylinder chamber 37 c.

The lower end opening of the high-stage cylinder hole 38b of the high-stage cylinder 38a is closed by the 2 nd bearing 42, and the upper end opening of the high-stage cylinder hole 38b is closed by the partition plate 39. A space defined by the high-stage cylinder 38a, the 2 nd bearing 42, and the partition plate 39 is a high-stage cylinder chamber 38 c.

The low-stage cylinder 37a and the high-stage cylinder 38a are axially butted with each other with a partition plate 39 interposed therebetween. The specific structure of the partition plate 39 will be described later.

The rotary shaft 31 includes a low-stage-side eccentric portion 31b that is eccentric to the center axis C in a radial direction at a position located in the low-stage-side cylinder chamber 37C. The rotary shaft 31 includes a high-stage-side eccentric portion 31d that is eccentric to the center axis C toward the other radial side at a position located in the high-stage-side cylinder chamber 38C.

The rotary shaft 31 includes, as a main shaft extending about the center axis C, a1 st main shaft 31a extending above the low-stage-side eccentric portion 31b, a 2 nd main shaft 31C extending between the low-stage-side eccentric portion 31b and the high-stage-side eccentric portion 31d, and a 3 rd main shaft 31e extending below the high-stage-side eccentric portion 31 d. The 1 st main shaft 31a extends upward largely, and a rotor 36 of the electric motor 32 is fixed to the 1 st main shaft 31 a.

The

eccentric portions

31b and 31d are formed in cylindrical shapes having the same diameter as each other. The

eccentric portions

31b and 31d are arranged with a phase difference of 180 ° in the circumferential direction. The eccentric amounts of the

eccentric portions

31b and 31d with respect to the center axis C are the same.

The cylindrical low-stage side roller 45 is rotatably inserted externally to the low-stage side eccentric portion 31 b. The low-stage-side eccentric portion 31b and the low-stage-side roller 45 rotate about the center axis of the eccentric portion 31 b.

The cylindrical high-stage-side roller 46 is rotatably externally fitted to the high-stage-side eccentric portion 31 d. The high stage side eccentric portion 31d and the high stage side roller 46 rotate about the center axis of the eccentric portion 31 d.

The 1 st bearing 41 includes a cylindrical portion 41a rotatably supporting the 1 st spindle 31a of the rotary shaft 31, and a flange portion 41b formed to have a larger diameter on the outer peripheral side of the lower end portion of the cylindrical portion 41 a. The upper muffler component (2 nd muffler component) 43 is fixed to the 1 st bearing 41 by the bolt B2, for example.

The 2 nd bearing 42 includes a cylindrical tube portion 42a rotatably supporting the 3 rd spindle 31e of the rotary shaft 31, and a flange portion 42b formed by expanding the diameter of the outer peripheral side of the upper end portion of the tube portion 42 a. The bottom side muffler component (1 st muffler component) 44 is fixed to the 2 nd bearing 42.

Of the axial lengths L1, L2 of the sliding portions of the 1 st bearing 41 and the 2 nd bearing 42 that slide with respect to the rotary shaft 31, the sliding portion length L1 of the 1 st bearing 41 is longer than the sliding portion length L2 of the 2 nd bearing 42. Therefore, the deflection of the rotating shaft 31 on the 1 st bearing 41 side can be reduced, and the inclination of the low-stage side eccentric portion 31b and the low-stage side roller 45 can be reduced.

The eccentric portion 31b of the low-stage compression mechanism 37 is disposed axially offset toward the 1 st bearing 41 in the low-stage side cylinder chamber 37 c. In other words, the axial center position cp1 of the eccentric sliding portion (sliding portion between the eccentric portion 31b and the roller 45) of the low-stage compression mechanism portion 37 is located closer to the 1 st bearing 41 in the axial direction than the axial center position cp2 of the low-stage side cylinder 37a of the low-stage compression mechanism portion 37. This also reduces the deflection of the rotating shaft 31 on the 1 st bearing 41 side.

The low-stage compression mechanism 37 includes vanes (low-stage-side vanes) 18 that divide the low-stage-side cylinder chamber 37c into two parts, i.e., the suction chamber 16 and the compression chamber 17. The vane 18 is provided in a vane groove 18c formed in the low-stage side cylinder 37a and can move forward and backward with respect to the cylinder chamber 37 c. The vane 18 maintains a state in which the roller 45 side tip end surface (roller contact surface) 18a is in contact with the outer peripheral surface of the roller 45. The vane 18 and the roller 45 divide the interior of the cylinder chamber 37c into a suction chamber 16 and a compression chamber 17.

The vane 18 of the low-stage compression mechanism 37 is composed of, for example, a plurality of (a pair of upper and lower in the embodiment) vane members (low-stage-side vane members) 19a and 19b provided to overlap in the axial direction. Hereinafter, the upper and

lower blade members

19a and 19b may be simply referred to as the blade member 19.

The vane 18 (vane member 19) is biased toward the roller 45 by receiving the housing internal pressure only at the back surface 18b opposite to the front end surface 18a in the radial direction (forward and backward direction) of the cylinder chamber 37 c. No biasing member such as a spring is provided on the back surface 18b side of the blade 18. The tip end surface 18a of the blade 18 is, for example, arcuate when viewed in the axial direction. The tip end surface 18a of the blade 18 is subjected to surface hardening treatment such as DLC coating. The back surface 18b of the blade 18 is flat, for example, perpendicular to the forward/backward direction when viewed in the axial direction. In the figure, reference numeral 34c denotes a case internal communication portion which communicates with the inside of the sealed case 34 and in which the case internal pressure acts.

The vane 18 (a pair of

vane members

19a and 19b) is slidably held in the vane groove 18 c. The pair of

blade members

19a and 19b can slide (advance and retreat) in the radial direction independently of the blade groove 18 c.

The vane 18 is biased radially inward (toward the roller 45) by the pressure of the high-pressure gas refrigerant in the sealed casing 34 (casing internal pressure). Thereby, the vane 18 is maintained in contact with the outer peripheral surface of the eccentrically rotating roller 45.

The low-stage compression mechanism 37 performs a compression operation in the low-pressure side cylinder chamber 37c by the eccentric rotation operation of the roller 45 and the forward and backward movement operation of the vane 18.

A suction hole 18d that penetrates the low-stage side cylinder 37a in the radial direction is formed in a part of the low-stage side cylinder 37a in the circumferential direction. The suction hole 18d is located on the downstream side of the vane groove 18c (on the left side of the vane groove 18c in fig. 3) in the eccentric rotation direction of the roller 45 (also in the direction of arrow F in fig. 3, the rotation direction of the rotary shaft 31). A suction pipe 6 extending from the reservoir 12 is connected to the radially outer side of the suction hole 18 d.

Note that, although the high-stage compression mechanism 38 is not shown in the same manner as in fig. 3, referring to fig. 2, the high-stage compression mechanism 38 also includes a vane (high-stage-side vane) 21 that divides the cylinder chamber 38c into two parts, i.e., the suction chamber 16 and the compression chamber 17, as in the low-stage compression mechanism 37. The vane 21 of the high-stage compression mechanism portion 38 is constituted by one vane member (high-stage-side vane member) 22. In the figure, reference numeral 21a denotes a front end surface of the blade 21, and reference numeral 21b denotes a rear surface of the blade 21.

The blade member 22 is biased toward the roller 46 by receiving the housing internal pressure at the back surface 21b, and is also biased toward the roller 46 by compressing a biasing spring 23 (e.g., a coil spring) provided on the back surface 21b side. The high-stage compression mechanism 38 includes the biasing spring 23 that biases the vane member 22, and thus, even in a state where the internal pressure of the casing is low such as when the multistage rotary compressor 2 is started, the vane member 22 can be biased toward the roller 46, and the sucked refrigerant can be compressed and pressurized.

In each of the

compression mechanism portions

37 and 38, the eccentric rotation of the

rollers

45 and 46 causes a suction operation of sucking the gas refrigerant into the suction chamber 16 and a compression operation of compressing the gas refrigerant in the compression chamber 17.

In the low-stage compression mechanism 37, low-pressure gas refrigerant is sucked from the accumulator 12 by the suction operation. In the low-stage compression mechanism 37, the sucked gas refrigerant is compressed by the compression operation and is boosted to an intermediate pressure. The gas refrigerant pressurized by the low-stage compression mechanism 37 is discharged into the intermediate pressure chamber 39c of the partition plate 39 through the discharge hole 47a provided in the partition plate 39.

In the high-stage compression mechanism 38, the intermediate-pressure gas refrigerant is sucked from the intermediate pressure chamber 39c by the suction operation. In the high-stage compression mechanism 38, the sucked gas refrigerant is further compressed by the compression action and is pressurized to a high pressure. The gas refrigerant pressurized by the high-stage compression mechanism 38 is discharged to the outside of the cylinder chamber 38c (into the bottom muffler chamber 44a) through the discharge hole 49a provided in the flange portion 42b of the 2 nd bearing 42.

The partition plate 39 is formed in a ring shape centered on the axis C. The partition plate 39 has an inner diameter through which the rotary shaft 31 including the

eccentric portions

31b and 31d can be inserted. The inner diameter of the partition plate 39 needs to be larger than the outer diameter of at least one of the

eccentric portions

31b and 31d of the rotary shaft 31. Therefore, the intermediate pressure space 39c in the partition plate 39 is formed to be expanded toward the outer peripheral side, rather than being expanded toward the inner peripheral side.

The partition plate 39 is divided into a plurality of (a pair of upper and lower

partition plate members

39a, 39b in the embodiment) in the axial direction. The

partition members

39a and 39b each have a concave cross-sectional shape with the other side recessed and extend annularly. The

partition members

39a and 39b are connected to each other in a state where the open side of the concave cross-sectional shape is directed to the other side. Thereby, an intermediate pressure space (intermediate pressure chamber) 39c is formed inside the partition plate 39. By dividing the partition plate 39, the intermediate pressure space 39c can be easily formed, and the low-stage side discharge valve device 47 can be easily provided in the partition plate 39. Of the

partition members

39a and 39b, the partition member positioned on the lower stage side may be referred to as a lower stage side partition member 39a, and the partition member positioned on the higher stage side may be referred to as a higher stage side partition member 39 b.

By providing the intermediate pressure space 39c in the partition plate 39, the volume of the intermediate pressure space 39c can be secured. This can suppress discharge pulsation of the gas refrigerant discharged from the low-stage compression mechanism unit 37 and suction pulsation of the gas refrigerant sucked into the high-stage compression mechanism unit 38.

The low-stage side partition plate member 39a is provided with a low-stage side discharge valve device 47, and the low-stage side discharge valve device 47 discharges the intermediate-pressure gas refrigerant compressed by the low-stage compression mechanism 37 into the intermediate pressure space 39 c.

The intermediate-pressure gas refrigerant discharged from the low-stage compression mechanism 37 into the intermediate pressure space 39c is guided to the 2 nd suction portion 14a communicating with the high-stage compression mechanism 38 through the intermediate pressure passage 7. The intermediate-pressure gas refrigerant guided to the high-stage compression mechanism unit 38 through the intermediate pressure passage 7 is cooled by the intercooler 7a in the middle. Therefore, the cooled intermediate-pressure gas refrigerant is guided to the high-stage compression mechanism unit 38. The intermediate-pressure gas refrigerant gas-liquid-separated in the 2 nd accumulator 8 is guided through the bypass passage 8a merging in the middle of the intermediate-pressure passage 7. The intermediate-pressure gas refrigerant guided to the 2 nd suction portion 14a is compressed by the high-stage compression mechanism portion 38.

In the multistage rotary compressor 2, when the gas refrigerant compressed in the low-stage compression mechanism 37 has a predetermined intermediate pressure, the low-stage discharge valve device 47 of the low-stage partition plate member 39a is opened. When the low-stage side discharge valve device 47 of the partition plate 39 is opened, the intermediate-pressure gas refrigerant is discharged into the intermediate pressure space 39 c. The gas refrigerant is guided into the cylinder chamber 38c of the high-stage compression mechanism 38. Thereafter, the intermediate-pressure gas refrigerant is compressed into a high-pressure gas refrigerant by the compression operation of the high-stage compression mechanism 38.

A high-stage side discharge valve device 49 is provided in the flange portion 42b of the 2 nd bearing 42, and the high-stage side discharge valve device 49 discharges the high-pressure gas refrigerant compressed by the high-stage compression mechanism portion 38 to the outside of the cylinder chamber 38 c.

In the multistage rotary compressor 2, when the gas refrigerant compressed in the high-stage compression mechanism 38 has a predetermined high pressure, the high-stage discharge valve device 49 of the 2 nd bearing 42 is opened. When the high-stage-side discharge valve device 49 is opened, the high-pressure gas refrigerant is discharged to the outside of the cylinder chamber 38 c. The gas refrigerant is discharged into the space (bottom muffler chamber 44a) in the bottom muffler component 44, and then appropriately discharged into the sealed housing 34.

Specifically, the high-pressure gas refrigerant discharged into the bottom muffler chamber 44a passes through the discharge passage 33a in the compression element 33 and reaches the space (the upper muffler chamber 43a) in the upper muffler member 43. For example, the discharge passage 33a is formed to penetrate the outer peripheral sides of the 2 nd bearing 42, the low-stage cylinder 37a, the partition plate 39, the high-stage cylinder 38a, and the 1 st bearing 41 in the axial direction. The gas refrigerant that has reached the upper muffler chamber 43a is discharged into the sealed casing 34 through a discharge hole provided appropriately in the upper muffler component 43.

The bottom muffler component 44 has a container shape covering the 2 nd bearing 42 from below. A lower end communication hole for exposing the lower end of the rotary shaft 31 downward (out of the muffler) is formed in the center portion of the lower wall of the bottom muffler component 44. An oil supply passage for sucking the lubricating oil J into the rotary shaft 31 through the lower end communication hole.

The upper silencer component 43 has a container shape covering the 1 st bearing 41 from above. A shaft insertion hole through which the rotating shaft 31 is inserted is formed in the central portion of the upper wall portion of the upper silencer component 43, and an upper end communication hole that communicates the inside and the outside of the upper silencer component 43 is formed around the shaft insertion hole. The high-temperature and high-pressure gas refrigerant flowing into the upper muffler chamber 43a is discharged into the sealed housing 34 through the upper end communication hole.

The upper muffler chamber 43a is formed around the 1 st bearing 41 on the low stage side. The flange 41b of the 1 st bearing 41 that closes the upper end of the lower stage side cylinder chamber 37c is formed on the inner wall surface of the lower end of the upper muffler chamber 43 a.

The bottom side muffler chamber 44a is formed around the 2 nd bearing 42 on the high stage side. In a range where the bottom-side muffler components 44 are immersed in the lubricating oil J of the lubricating oil reservoir 34b, the bottom-side muffler components 44 are formed on the inner wall surface of the bottom-side muffler chamber 44 a.

In the embodiment, the thickness of the portion of the bottom muffler component 44 that separates the inside of the bottom muffler chamber 44a from the lubricating oil reservoir 34b is smaller than the thickness of the portion of the 1 st bearing 41 that separates the inside of the upper muffler chamber 43a from the suction chamber 16 of the low-stage compression mechanism 37 (the flange portion 41 b).

In this configuration, the thickness of the divided portion of the bottom muffler chamber 44a is made thinner than the thickness of the divided portion of the upper muffler chamber 43 a. This can further increase the amount of heat released from bottom muffler chamber 44a to lubricating oil J, thereby improving the cooling performance of the working fluid. Further, the amount of heat released from the upper muffler chamber 43a to the suction chamber 16 of the low-stage compression mechanism 37 can be further reduced, and the influence of suction superheat on efficiency and reliability can be further suppressed. Therefore, the multistage rotary compressor 2 having high efficiency and high reliability can be provided.

In the embodiment, the surface area of the outer wall surface of the portion (bottom muffler component 44) separating the bottom muffler chamber 44a from the lubricating oil reservoir 34b may be larger than the surface area of the outer wall surface of the portion (flange 41b) separating the upper muffler chamber 43a from the suction chamber 16 of the low-stage compression mechanism 37. This also achieves the above-described effects.

In the embodiment, the heat transfer coefficient of the portion (bottom muffler member 44) separating the inside of the bottom muffler chamber 44a from the lubricating oil reservoir 34b may be set to be larger than the heat transfer coefficient of the portion (flange 41b) separating the inside of the upper muffler chamber 43a from the suction chamber 16 of the low-stage compression mechanism 37. For example, the bottom side muffler component 44 is formed of a copper alloy, and the 2 nd bearing 42 is formed of cast iron. This also achieves the above-described effects.

The lower end portion of the rotary shaft 31 is immersed in the lubricating oil J stored in the bottom portion of the hermetic case 34 together with the bottom-side muffler component 44.

An oil supply passage for supplying the lubricating oil J to each sliding portion of the compression element 33 is formed in the rotary shaft 31. The sliding portions of the compression element 33 are between the

eccentric portions

31b and 31d and the

rollers

45 and 46, between the rotary shaft 31 and the

bearings

41 and 42, between the

rollers

45 and 46 and the

vanes

18 and 21, and the like.

The rotary shaft 31 includes, as an oil supply passage, an axial passage 95 extending coaxially with the axis C, and a1 st radial passage 96 and a 2 nd radial passage 97 extending radially from the axial passage 95.

The lower end of the axial flow passage 95 opens downward at the lower end of the rotary shaft 31. The upper end of the axial flow passage 95 terminates in the 1 st main shaft 31a above the low-stage side cylinder 37 a. The lubricating oil J in the sealed casing 34 can flow into the axial flow passage 95.

The 1 st radial flow path 96 is formed at a connection portion between the 1 st main shaft 31a and the low-stage side eccentric portion 31b in the rotary shaft 31. The radial inner end of the 1 st radial flow passage 96 is open into the axial flow passage 95. The radial outer end of the 1 st radial flow passage 96 is open radially outward on the outer circumferential surface of the rotary shaft 31 (in the figure, in an oil groove extending in the circumferential direction).

The 2 nd radial flow passage 97 is formed in the rotary shaft 31 at a connection portion between the 3 rd main shaft 31e and the high stage side eccentric portion 31 d. The radial inner end of the 2 nd radial flow passage 97 opens into the axial flow passage 95. The radial outer end of the 2 nd radial flow passage 97 is open radially outward on the outer circumferential surface of the rotary shaft 31 (in the figure, in an oil groove extending in the circumferential direction).

When the pressure in the casing rises due to the driving of the compression element 33, the lubricating oil J is pushed out into the axial flow path 95 from the lower end of the rotary shaft 31. The lubricating oil J is distributed from the axial flow passage 95 to the

radial flow passages

96 and 97 by the centrifugal force generated by the rotation of the rotary shaft 31. The lubricating oil J that has reached the

radial flow passages

96 and 97 flows out on the outer peripheral surface of the rotary shaft 31 and is appropriately supplied to the sliding portion of the compression element 33.

For example, the lubricating oil J flowing out of the 1 st radial flow passage 96 is supplied to the 1 st bearing 41, the low-stage compression mechanism 37, and the like. The lubricating oil J flowing out of the 2 nd radial flow passage 97 is supplied to the high-stage compression mechanism unit 38, the 3 rd main shaft 31e, the 2 nd bearing 42, and the like. The lubricating oil J supplied to each sliding portion flows down and returns to the bottom of the sealed casing 34, and is supplied again to the sliding portion of the compression element 33.

In the embodiment, the working fluid is discharged from the high-stage compression mechanism 38 into the sealed casing 34, and the lubricating oil J is stored in the bottom of the sealed casing 34. The lubricating oil J in the closed casing 34 is guided from the 1 st radial flow passage 96 to the inner peripheral side of the low-stage side roller 45 of the low-stage compression mechanism unit 37, and is supplied into the low-stage side cylinder chamber 37c via the roller end face seal unit 45 a. The axial dimension difference between the low-stage side cylinder 37a and the low-stage side roller 45 in the low-stage compression mechanism 37 is smaller than the axial dimension difference between the high-stage side cylinder 38a and the high-stage side roller 46 in the high-stage compression mechanism 38.

In this configuration, in the roller end face seal portion 45a of the low-stage compression mechanism portion 37 in which the differential pressure is large, the gap between the end face of the roller 45 and the partition plate 39 and the 1 st bearing 41 is reduced, and the lubricating oil J can be prevented from excessively flowing into the low-stage side cylinder chamber 37 c.

Further, since the axial dimension difference between the

cylinders

37a and 38a and the

rollers

45 and 46 is set as described above, the sealing performance at the roller end face seal portion 45a of the low stage compression mechanism portion 37 having a large differential pressure can be improved, while the risk of shortage of the supply amount of the lubricating oil J into the high stage side cylinder chamber 38c can be reduced in the roller end face seal portion 46a of the high stage compression mechanism portion 38 having a small differential pressure, and the high stage side sliding loss can be reduced.

Next, the operation of the multistage rotary compressor 2 will be described.

When the multistage rotary compressor 2 is started, when electric power is supplied to the stator 35 of the electric motor 32, the rotary shaft 31 rotates about the axis C together with the rotor 36. When the rotary shaft 31 rotates, the

eccentric portions

31b and 31d of the two

compression mechanism portions

37 and 38 and the

rollers

45 and 46 rotate eccentrically in the

cylinder chambers

37c and 38 c.

At this time, the

rollers

45 and 46 of the two

compression mechanism sections

37 and 38 are in rolling contact with the inner circumferential surfaces of the

cylinder chambers

37c and 38c via an oil film, but the

vanes

18 and 21 are as follows. That is, the vane 21 of the high-stage compression mechanism 38 is in sliding contact with the roller 46 by the biasing force of the biasing spring 23. The vane 18 of the low-stage compression mechanism 37 is kept in a state of being submerged in the vane groove 18c while the casing internal pressure is kept low. Therefore, when the multistage rotary compressor 2 is started, only the cylinder chamber 38c of the high-stage compression mechanism 38 is divided into the suction side and the compression side, and the gas refrigerant is compressed.

Finally, when the closed casing 34 is filled with the high-pressure gas refrigerant discharged from the high-stage compression mechanism 38, the vane 18 of the low-stage compression mechanism 37 is urged toward the roller 45 by the casing internal pressure and starts to slide on the roller 45. Then, the cylinder chamber 37c of the low-stage compression mechanism 37 is also partitioned into a suction side and a compression side, and compression of the gas refrigerant is started.

Thereafter, the low-pressure gas refrigerant subjected to gas-liquid separation in the accumulator 12 is guided into the cylinder chamber 37c of the low-stage compression mechanism 37 via the suction pipe 6. The low-pressure gas refrigerant guided into the cylinder chamber 37c is compressed by the low-stage compression mechanism 37 to have a predetermined intermediate pressure. When the gas refrigerant has reached a predetermined intermediate pressure, the low-stage-side discharge valve device 47 of the partition plate 39 is opened, and the gas refrigerant of the intermediate pressure is discharged into the intermediate pressure space 39c of the partition plate 39.

The gas refrigerant discharged to the intermediate pressure space 39c is sucked into the high-stage compression mechanism 38 through the intermediate pressure passage 7 and the bypass passage 8 a.

The gas refrigerant sucked into the high-stage compression mechanism 38 is boosted from the intermediate pressure to a predetermined high pressure. When the gas refrigerant has a predetermined high pressure, the high-stage discharge valve device 49 of the 2 nd bearing 42 is opened, and the high-pressure gas refrigerant is discharged into the 2 nd muffler chamber 44 a. The gas refrigerant discharged into the 2 nd muffler chamber 44a reaches the 1 st muffler chamber 43a from the discharge passage 33a, and is then appropriately discharged into the hermetic case 34.

The high-pressure gas refrigerant discharged into the sealed casing 34 circulates through the radiator 3, the expansion device 4, the evaporator 5, and the like, and returns to the low-pressure gas refrigerant. The gas refrigerant returned to the low pressure is again guided into the cylinder chamber 37c of the low-stage compression mechanism 37, and the above-described stroke is repeated.

The 1 st and 3 rd

main shafts

31a and 31e of the rotation shaft 31 have the same diameter with each other. Hereinafter, the 1 st spindle 31a and the 3 rd spindle 31e may be collectively referred to as a spindle 31 j. Of the members assembled to the rotary shaft 31, the 1 st bearing 41 and the rotor 36 are assembled to the rotary shaft 31 from the upper end side. Of the members assembled to the rotary shaft 31, the low-stage-side rollers 45, the partition plate 39, the high-stage-side rollers 46, and the 2 nd bearing 42 are assembled to the rotary shaft 31 from the lower end side.

Here, a procedure for assembling the low-stage side roller 45 to the rotary shaft 31 will be described with reference to fig. 4. Hereinafter, the radius of the main shaft 31j of the rotary shaft 31 is denoted by Rj, the radius and the eccentric amount of the eccentric portion 31b of the low-stage compression mechanism unit 37 are denoted by R1 and E1, respectively, and the radius and the eccentric amount of the eccentric portion 31d of the high-stage compression mechanism unit 38 are denoted by R2 and E2, respectively.

Referring to fig. 4 (a), first, the low-stage-side roller 45 is moved from the lower end side of the rotary shaft 31 to the high-stage-side eccentric portion 31d in the axial direction. At this time, the inner radius of the low-stage side roller 45 (corresponding to the radius R1 of the low-stage side eccentric portion 31 b) needs to be equal to or larger than the radius R2 of the high-stage side eccentric portion 31 d. That is, the relational expression "R1 ≧ R2" needs to be satisfied. In order to move the low-stage side roller 45 from the 3 rd main shaft 31E to the high-stage side eccentric portion 31d in the axial direction, the radius R2 of the high-stage side eccentric portion 31d needs to be equal to or greater than the value obtained by adding the radius RJ of the 3 rd main shaft 31E to the eccentric amount E2. That is, the relational expression "R2 ≧ Rj + E2" needs to be satisfied.

Referring to fig. 4 (b) and 4 (c), after the low-stage side roller 45 is moved in the axial direction to the high-stage side eccentric portion 31d, the low-stage side roller 45 is further moved in the axial direction so as to overlap the 2 nd main shaft 31c in the axial direction position. In this state, the low-stage-side roller 45 is moved in the eccentric direction of the low-stage-side eccentric portion 31b (fig. 4 (c)), and the low-stage-side roller 45 is disposed coaxially with the low-stage-side eccentric portion 31 b. In order to move the low-stage-side roller 45 in the eccentric direction of the low-stage-side eccentric portion 31b, the axial length of the 2 nd main shaft 31c (the interval between the two

eccentric portions

31b and 31 d) needs to be equal to or longer than the axial length of the low-stage-side roller 45.

Referring to fig. 4 (d), after the low-stage side roller 45 is disposed coaxially with the low-stage side eccentric portion 31b, the low-stage side roller 45 is moved in the axial direction to be externally inserted into the low-stage side eccentric portion 31 b. In the outer peripheral portion of the low-stage-side eccentric portion 31b on the opposite side to the eccentric direction, the outer peripheral surface of the low-stage-side eccentric portion 31b and the outer peripheral surface of the 2 nd main shaft 31c are aligned in a substantially flush plane. The outer peripheral surface (outer peripheral edge) of the 2 nd main shaft 31c converges inside the outer peripheral surface (outer peripheral edge) of the lower-stage eccentric portion 31b as viewed in the axial direction. The outer diameter of the low-stage-side eccentric portion 31b is substantially the same as the inner diameter of the low-stage-side roller 45. This allows the low-stage-side roller 45 to be moved in the axial direction and externally inserted into the low-stage-side eccentric portion 31 b.

Since the pressure of the working fluid sucked into the low-stage compression mechanism portion 37 is lower than that of the high-stage compression mechanism portion 38, the suction volume (excluded volume) needs to be increased. Therefore, the eccentric amounts E1 and E2 of the two

eccentric portions

31b and 31d have a relationship of "E1 > E2". The inner radius (radius of the low-stage-side eccentric portion 31 b) R1 of the low-stage-side roller 45 needs to be smaller than a value obtained by adding the radius RJ of the main shaft 31j to the eccentric amount E1. That is, the relation "R1 < Rj + E1" needs to be satisfied.

As described above, in the embodiment, all of the following relational expressions (1) to (4) are satisfied.

E1>E2……(1)

R1<Rj+E1……(2)

R2≧Rj+E2……(3)

R1≧R2……(4)

With this configuration, the low-stage side roller 45 can be assembled without reducing the shaft diameter of the 3 rd main shaft 31e on the lower end side of the rotary shaft 31 and the shaft diameter of the 2 nd main shaft 31c between the two

eccentric portions

31b and 31 d.

Referring to fig. 1 and 2, in the embodiment, the low-stage compression mechanism 37 is disposed on the electric motor 32 side of the compression element 33.

In this configuration, when the low-stage-side roller 45 is assembled to the low-stage-side eccentric portion 31b, the low-stage-side roller 45 can be assembled from the side of the rotating shaft 31 to which the electric motor 32 is not coupled. Since the 1 st main shaft 31a of the rotary shaft 31 on the electric motor 32 side is long, the multistage rotary compressor 2 can be easily assembled and manufactured with high productivity by assembling the low-stage side roller 45 from the side of the rotary shaft 31 opposite to the electric motor 32.

The low-stage-side partition plate (low-stage-side partition plate member 39a) is provided with a low-stage discharge hole 47a for discharging the intermediate-pressure working fluid compressed by the low-stage compression mechanism 37 to the intermediate pressure space 39 c. The low-stage discharge hole 47a penetrates the upper wall portion of the low-stage side partition plate member 39a in the axial direction. A low-stage-side discharge valve device 47 for opening and closing the low-stage discharge hole 47a is disposed in the low-stage-side partition plate member 39 a.

Referring also to fig. 5, the low-stage-side discharge valve device 47 includes a low-stage valve seat 47b formed around the low-stage discharge hole 47a, a low-stage valve member 47c that opens and closes the low-stage discharge hole 47a, and a low-stage valve pressing member (retainer) 47d that restricts the maximum lift amount of the low-stage valve member 47 c. The low-stage valve member 47c is a leaf valve in the form of an elastic plate, and is biased toward the low-stage valve seat 47b in the axial direction. Before the pressure in the cylinder chamber 37c (compression chamber 17) rises, the low-stage-side discharge valve device 47 closes the low-stage discharge hole 47 a. As the pressure in the cylinder chamber 37c (compression chamber 17) increases, the low-stage-side discharge valve device 47 opens the low-stage discharge hole 47a, and the refrigerant is discharged to the outside of the cylinder chamber 37 c.

The flange 42b of the high-stage-side 2 nd bearing 42 is provided with a high-stage discharge hole 49a for discharging the working fluid compressed by the high-stage compression mechanism 38 to the outside of the compression element 33 (into the closed casing 34). The high-stage discharge hole 49a penetrates the flange portion 42b in the axial direction. A high-stage-side discharge valve device 49 for opening and closing the high-stage discharge hole 49a is disposed in the flange portion 42 b.

The high-stage-side discharge valve device 49 includes a high-stage valve seat 49b formed around the high-stage discharge hole 49a, a high-stage valve member 49c for opening and closing the high-stage valve seat 49b, and a high-stage valve pressing member (retainer) 49d for limiting the maximum lift amount of the high-stage valve member 49 c. The high-stage valve member 49c is a leaf valve of an elastic plate shape, and is biased toward the high-stage valve seat 49b in the axial direction. Before the pressure in the cylinder chamber 38c (compression chamber 17) rises, the high-stage discharge valve device 49 closes the high-stage discharge hole 49 a. As the pressure in the cylinder chamber 38c (compression chamber 17) increases, the high-stage discharge valve device 49 opens the high-stage discharge hole 49a, and the refrigerant is discharged to the outside of the cylinder chamber 38 c.

In the embodiment, the intermediate pressure space 39c is expanded to suppress pulsation of the intermediate-pressure refrigerant discharged from the low-stage discharge hole 47 a. In order to increase the intermediate pressure space 39c, the following configuration is adopted in the embodiment.

That is, in the embodiment, the thickness T1 in the axial direction (biasing direction) of the portion 39d of the low-stage side partition plate member 39a where the low-stage valve seat 47b is formed is made smaller than the thickness T2 in the axial direction (biasing direction) of the portion 42d of the 2 nd bearing 42 where the high-stage valve seat 49b is formed.

In this way, the volume of the intermediate pressure space 39c formed in the partition plate 39 can be increased by making the thickness T1 of the portion 39d where the low-stage valve seat 47b is formed smaller than the thickness T2 of the portion 42d where the high-stage valve seat 49b is formed. Therefore, pulsation of the intermediate-pressure refrigerant discharged from the low-stage discharge hole 47a is suppressed, and flow loss of the discharge fluid on the low-stage side can be reduced.

In general, the pressure difference acting on the valve seat 47b of the low-stage-side discharge valve device 47 is smaller than the pressure difference acting on the valve seat 49b of the high-stage-side discharge valve device 49. Therefore, even if the thickness T1 of the valve seat forming portion 39d on the low stage side is reduced, the risk of deformation in the vicinity of the valve seat 47b is small. On the other hand, since the pressure difference acting on the valve seat 49b of the high-stage-side discharge valve device 49 is relatively large, it is difficult to reduce the thickness T2 of the high-stage-side valve seat forming portion 42d in order to secure strength.

Further, the volume of the low-stage side working fluid discharged from the low-stage compression mechanism portion 37 is larger than the volume of the high-stage side working fluid discharged from the high-stage compression mechanism portion 38. Therefore, it is preferable to secure the capacity of the intermediate pressure space 39c formed in the partition plate 39 as large as possible.

In the configuration of the embodiment, it is possible to provide the multistage rotary compressor 2 which is capable of suppressing deformation around the high-stage valve seat 49b while increasing the sectional area of the intermediate pressure space 39c, and which has high performance and high reliability.

In the embodiment, the low-stage valve member 47c is set to open at a pressure difference smaller than that of the high-stage valve member 49 c.

By opening the low-stage valve member 47c with a pressure difference smaller than that of the high-stage valve member 49c, the configuration effective for reducing the excessive compression loss is achieved, and the multistage rotary compressor 2 can be further efficiently operated.

That is, on the low stage side where the flow rate of the working fluid is large, the delay in opening of the discharge valve has a large influence on the excess compression loss. Further, on the low stage side where the discharge pressure is low, the ratio of the differential pressure required for opening the valve to the discharge pressure is large, and therefore the ratio of the excess compression loss to the total loss tends to increase. For example, in a configuration in which the low-stage compression mechanism 37 compresses the working fluid from 1Mpa to 2Mpa and the high-stage compression mechanism 38 compresses the working fluid from 2Mpa to 4Mpa, when the

valve members

47c and 49c are opened with a differential pressure of the target pressure +0.2Mpa, the ratio of the differential pressure required for opening the valve to the discharge pressure (2.2Mpa) of the low-stage compression mechanism 37 is greater than that of the high-stage compression mechanism 38.

For example, the valve opening differential pressure of the

valves

47c and 49c is changed by making the thickness, length, material, and the like of the

valves

47c and 49c different from each other. For example, the thickness of the low-stage valve member 47c is made thinner than the thickness of the high-stage valve member 49 c. By reducing the thickness of the low-stage valve member 47c, the spring rigidity of the low-stage valve member 47c can be easily reduced, and the valve opening differential pressure can be easily changed. By securing the thickness of the high-stage valve member 49c, which has a large differential pressure applied when the valve is closed, the risk of valve breakage is reduced, and the multistage rotary compressor 2 having high reliability is obtained.

In addition, when the diameter of the low stage discharge hole 47a is set to

The diameter of the high-stage discharge hole 49a is set to

When the maximum lift amount of the low-stage valve member 47c is L1 and the maximum lift amount of the high-stage valve member 49c is L2, the following relational expressions (5) and (6) are satisfied.

L1≦L2……(6)

In the case where a retainer for limiting the lift amount of the valve material is provided, the following problems arise when the maximum lift amount is increased in order to reduce the flow path loss of the discharge fluid in the low-stage-side discharge valve device 47. That is, it is necessary to increase the thickness of the partition plate 39 in the axial direction in order to secure the intermediate pressure space 39c, and it is considered that the reliability is affected by an increase in the deflection of the rotary shaft 31 due to an increase in the distance between the shafts.

In the embodiment, the maximum lift amount is not increased and only the diameter of the low stage discharge holes 47a is increased, thereby having the following effects. That is, since the flow path loss of the low-stage side discharge fluid can be suppressed without increasing the thickness of the partition plate, the multistage rotary compressor 2 having high performance and high reliability can be provided.

When the distance between the center axis C1 of the low stage discharge hole 47a and the center axis C of the rotary shaft 31 is S1 and the distance between the center axis C2 of the high stage discharge hole 49a and the center axis C of the rotary shaft 31 is S2, the following relational expression (7) is established.

S1>S2……(7)

In the embodiment, the center axis C1 of the low stage discharge hole 47a formed in the partition plate 39 is arranged on the outer circumferential side of the center axis C2 of the high stage discharge hole 49a provided in the 2 nd bearing 42 in the radial direction opposite to the rotation center axis C of the rotary shaft 31.

By positioning the center of the low stage discharge hole 47a on the outer peripheral side of the center of the high stage discharge hole 49a, the low stage side discharge can be performed without loss.

That is, in the annular partition plate 39, the low-stage discharge hole 47a can be disposed so as to be close to the center (center axis C) of the intermediate pressure space 39C that expands toward the outer peripheral side, and therefore, the discharge loss on the low-stage side can be suppressed. Therefore, the multistage rotary compressor 2 can be further efficiently operated.

Referring to fig. 5, of the

discharge ports

47a, 49a facing the

respective cylinder chambers

37c, 38c, only the low-stage discharge port 47a is provided with a discharge notch portion 47a1 that communicates the opening portion with the cylinder chamber 37 c.

The low-stage discharge holes 47a have a larger refrigerant flow rate and a larger hole diameter than the high-stage discharge holes 49a, and the hole positions are located further on the outer peripheral side. Therefore, by providing the discharge notch portion 47a1 in the inner peripheral portion of the low-stage side cylinder 37a, the low-stage discharge hole 47a can be prevented from being blocked by the inner peripheral portion of the low-stage side cylinder 37a, and the low-stage side discharge can be performed without further loss.

On the other hand, on the high stage side where the flow rate is small, the loss due to the discharge notch 47a1 becoming an ineffective volume may exceed the reduction in the discharge flow path loss due to the discharge notch 47a 1. Therefore, in the embodiment, the discharge notch portion 47a1 is not provided on the high stage side, and thus an increase in loss due to dead volume is prevented, and the discharge flow path loss is reduced on the low stage side, thereby achieving further efficiency.

In the embodiment, when the radius of the shaft portion of the rotary shaft 31 supported by the 1 st bearing 41 and the 2 nd bearing 42 is Rj, the radius and the eccentric amount of the eccentric portion 31b in the low-stage compression mechanism portion 37 are R1 and E1, respectively, and the radius and the eccentric amount of the eccentric portion 31d in the high-stage compression mechanism portion 38 are R2 and E2, respectively, at least all of the following relational expressions (1) to (4) are satisfied.

E1>E2……(1)

R1<Rj+E1……(2)

R2≧Rj+E2……(3)

R1≧R2……(4)

In this configuration, the roller 45 attached to the low-stage eccentric portion 31b can be assembled from the high-stage side, and the performance of the multistage rotary compressor 2 can be improved by securing the shaft diameter of the rotary shaft 31.

That is, when the volume of the low-stage-side compression chamber 17 is made larger than the volume of the high-stage-side compression chamber 17, by setting E1> E2 in the relational expression (1), the difference in volume between the low-stage-side and high-stage-side compression chambers 17 can be easily obtained without a large change in cylinder size.

Further, in the low-stage compression mechanism portion 37, since the pressure is low, the axial load is also small without increasing the radius R1 of the low-stage-side eccentric portion 31 b. In contrast, in the low-stage compression mechanism portion 37, the radius R1 is preferably small in order to reduce the sliding friction between the roller 45 and the eccentric portion 31b and ensure the sealing area of the roller end face. Therefore, R1< Rj + E1 satisfying the relation (2) is preferable.

However, when only the relational expression (2) is satisfied, in order to assemble the roller 45 to the low-stage-side eccentric portion 31b, it is necessary to reduce the shaft diameter of one of the shaft portions supported by the 1 st bearing 41 and the 2 nd bearing 42 in the rotary shaft 31 and also to reduce the shaft diameter of the shaft portion between the two

eccentric portions

31b and 31d on the low-stage side and the high-stage side. In this case, the rotary shaft 31 is easily bent, and reliability and performance are deteriorated.

In the configuration of the embodiment, by setting E1> E2 of the relational expression (1) and satisfying R2 ≧ Rj + E2 of the relational expression (3) and R1 ≧ R2 of the relational expression (4), R1< Rj + E1 of the relational expression (2) can be satisfied without reducing the shaft diameter of one of the shaft portions supported by the 1 st bearing 41 and the 2 nd bearing 42, or without reducing the shaft diameter of the shaft portion between the two

eccentric portions

31b and 31 d. Therefore, deflection of the rotary shaft 31 is suppressed, the sliding loss on the low stage side is reduced, and the airtightness of the roller end surface is improved. Therefore, the multistage rotary compressor 2 having high performance and high reliability can be obtained.

In the embodiment, the working fluid discharged from the high-stage compression mechanism unit 38 flows into the 1 st muffler chamber 44a having an inner wall surface formed by the 1 st member (bottom-side muffler member 44) contacting the lubricant oil reservoir 34b, and then is discharged into the casing through the 2 nd muffler chamber 43a having an inner wall surface formed by the flange portion 42b of the 2 nd bearing 42 contacting the suction chamber 16 of the low-stage compression mechanism unit 37.

In this configuration, the working fluid discharged from the high-stage compression mechanism 38 that has reached a high temperature is first cooled by heat dissipation from the inner wall surface to the lubricating oil J in the 1 st muffler chamber 44 a. Thereafter, the working fluid is further cooled in the 2 nd muffler chamber 43a by heat dissipation from the suction chamber 16 whose inner wall faces the low-stage compression mechanism portion 37 at the lowest temperature. Thereafter, the working fluid is discharged from the 2 nd muffler chamber 43a into the casing. Therefore, it is possible to reduce the risk of efficiency reduction, demagnetization of the magnet, and melting of the insulator, which are caused by overheating of the electric motor 32. Further, the working fluid first radiates heat to the lubricating oil J, so that the amount of heat radiated to the suction chamber 16 of the low-stage compression mechanism portion 37 can be reduced, and deterioration in efficiency and reliability due to suction overheat can be suppressed. Therefore, the multistage rotary compressor 2 having high efficiency and high reliability can be provided.

The refrigeration cycle apparatus 1 of the embodiment includes the multistage rotary compressor 2, the radiator 3 connected to the discharge portion 15 of the multistage rotary compressor 2, the expansion device 4 connected to the downstream side of the radiator 3, and the evaporator 5 connected between the downstream side of the expansion device 4 and the introduction portion 12a of the multistage rotary compressor 2.

In this configuration, the refrigeration cycle apparatus 1 includes the multistage rotary compressor 2, and thereby the following effects are obtained. That is, it is possible to provide the refrigeration cycle apparatus 1 capable of improving the operational reliability and the compression performance for a long period of time.

According to at least one embodiment described above, it is possible to provide the multistage rotary compressor 2 and the refrigeration cycle apparatus 1, in the multistage rotary compressor 2, in the partition plate 39 that partitions the space between the low-stage compression mechanism unit 37 and the high-stage compression mechanism unit 38, an intermediate pressure space 39c is formed in which the working fluid of the intermediate pressure compressed by the low-stage compression mechanism portion 37 is discharged, a low-stage discharge hole 47a and a low-stage side discharge valve device 47 are provided in the partition plate 39, a high-stage discharge hole 49a and a high-stage side discharge valve device 49 are provided in the 2 nd bearing 42 on the high-stage compression mechanism section 38 side, the thickness T1 of the portion of the partition plate 39 where the low-stage valve seat 47b is formed is smaller than the thickness T2 of the portion of the 2 nd bearing 42 where the high-stage valve seat 49b is formed, this can increase the capacity of the intermediate-pressure space 39c formed in the partition plate 39 and suppress pulsation of the intermediate-pressure working fluid.

Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the scope equivalent thereto.

Description of the symbols

1: a refrigeration cycle device; 2: a multistage rotary compressor; 3: a heat sink; 4: an expansion device; 5: a heat sink; 16: a suction chamber; 17: a compression chamber; 31: a rotating shaft; c: a central axis (rotation center); rj: spindle radius (radius); r1, R2: eccentric portion radius (radius); e1, E2: eccentricity amount; 32: an electric motor (driving element); 33: compressing the key element; 34: a hermetic case (housing); 34 b: a lubricating oil reservoir; 37: a low-stage compression mechanism section; 37 a: a low-stage side cylinder (cylinder); 37 c: a low-stage side cylinder chamber (cylinder chamber); 38: a high-stage compression mechanism section; 38 a: high-stage side cylinders (cylinders); 38 c: a high-stage side cylinder chamber (cylinder chamber); 39: a partition plate; 39 a: a low-stage-side partition member (partition member); 39 b: a high-stage-side partition plate member (partition plate member); 39 c: an intermediate pressure space; 41: the 1 st bearing (1 st member); 42: a 2 nd bearing; 44: a bottom side muffler component (1 st muffler component); 44 a: a bottom-side muffler chamber (1 st muffler chamber); 45: a low-stage side roller (roller); 45 a: a roller end face seal portion; 46: high-stage side rollers (rollers); 46 a: a roller end face seal portion; 47: a low-stage side discharge valve device; 47 a: a low-stage discharge port; c 1: a central axis (center); 47 b: a lower stage valve seat; 47 c: a low-grade valve material; 47 d: a part forming a bottom valve seat; t1: thickness; 49: a high-stage-side discharge valve device; 49 a: a high-grade discharge hole; c 2: a central axis (center); 49 b: a high-grade valve seat; 49 c: a high-grade valve material; 49 d: a portion forming a high-stage valve seat; t2: thickness; j: and (3) lubricating oil.

Claims

1. A multi-stage rotary compressor, in which,

a rotary shaft, a driving element provided on one axial end side of the rotary shaft, and a compressing element provided on the other axial end side of the rotary shaft are housed in a housing,

the compression element includes: a low-stage compression mechanism section for compressing a low-pressure working fluid to an intermediate pressure; a high-stage compression mechanism unit configured to compress the intermediate-pressure working fluid compressed by the low-stage compression mechanism unit into a high pressure; and a partition plate for partitioning the space between the low-stage compression mechanism unit and the high-stage compression mechanism unit,

a1 st bearing and a 2 nd bearing for pivotally supporting the rotary shaft are provided on the opposite sides of the partition plate of the low-stage compression mechanism section and the high-stage compression mechanism section,

the partition plate is formed by connecting a plurality of partition plate members in the axial direction of the rotary shaft,

an intermediate pressure space for discharging the working fluid of intermediate pressure compressed by the low-stage compression mechanism is provided between the partition members,

a low-stage-side partition member positioned on the low-stage compression mechanism unit side of the plurality of partition members is provided with a low-stage discharge hole for discharging the intermediate-pressure working fluid compressed by the low-stage compression mechanism unit to the intermediate pressure space, and a low-stage-side discharge valve device for opening and closing the low-stage discharge hole,

a high-stage discharge hole for discharging the working fluid compressed by the high-stage compression mechanism is formed in the 2 nd bearing located on the high-stage compression mechanism side, and a high-stage discharge valve device for opening and closing the high-stage discharge hole is provided,

the low-stage-side discharge valve device includes a low-stage valve seat formed around the low-stage discharge hole, and a low-stage valve member that comes into contact with the low-stage valve seat as a result of a biasing force,

the high-stage-side discharge valve device includes a high-stage valve seat formed around the high-stage discharge hole, and a high-stage valve member that comes into contact with the high-stage valve seat with application of force,

the thickness of the portion of the low-stage-side partition plate member where the low-stage valve seat is formed is smaller than the thickness of the portion of the 2 nd bearing where the high-stage valve seat is formed.

2. The multi-stage rotary compressor of claim 1,

the center of the low-stage discharge hole formed in the low-stage partition member is located on the outer peripheral side of the center of the high-stage discharge hole provided in the 2 nd bearing in the radial direction with respect to the rotation center of the rotary shaft.

3. The multi-stage rotary compressor of claim 1 or 2,

the low-stage valve member of the low-stage side discharge valve device opens at a pressure difference smaller than the high-stage valve member of the high-stage side discharge valve device.

4. The multi-stage rotary compressor of claim 1,

the low-stage compression mechanism portion and the high-stage compression mechanism portion each include a cylinder forming a cylinder chamber, and a roller attached to an eccentric portion of the rotary shaft and capable of eccentrically rotating in the cylinder chamber,

when the radius of the shaft portion of the rotary shaft supported by the 1 st bearing and the 2 nd bearing is Rj, the radius and the eccentric amount of the eccentric portion in the low-stage compression mechanism portion are R1 and E1, respectively, and the radius and the eccentric amount of the eccentric portion in the high-stage compression mechanism portion are R2 and E2, respectively, the following relational expressions (1) to (4) are all satisfied,

E1>E2……(1)

R1<Rj+E1……(2)

R2≧Rj+E2……(3)

R1≧R2……(4)。

5. the multi-stage rotary compressor of claim 4,

the working fluid compressed by the high-stage compression mechanism is discharged into the casing, and lubricating oil is stored in the bottom of the casing,

the lubricating oil in the casing is supplied to the cylinder chamber through a roller end face seal portion in the low-stage compression mechanism portion,

the axial dimension difference between the cylinder and the roller in the low-stage compression mechanism portion is smaller than the axial dimension difference between the cylinder and the roller in the high-stage compression mechanism portion.

6. The multi-stage rotary compressor of claim 4,

the low-stage compression mechanism is disposed on the drive element side of the compression element.

7. The multi-stage rotary compressor of claim 1,

a lubricant oil reservoir portion for storing lubricant oil for lubricating the compression element is provided at a bottom portion of the casing,

the working fluid discharged from the high-stage compression mechanism flows into the 1 st muffler chamber in contact with the lubricating oil reservoir, and is then discharged into the housing through the 2 nd muffler chamber in contact with the suction chamber of the low-stage compression mechanism.

8. The multi-stage rotary compressor of claim 7,

the thickness of the 1 st muffler component forming the 1 st muffler chamber is less than the thickness of the 2 nd muffler component forming the 2 nd muffler chamber.

9. The multi-stage rotary compressor of claim 7,

the thermal conductivity of the 1 st muffler component forming the 1 st muffler chamber is greater than the thermal conductivity of the 2 nd muffler component forming the 2 nd muffler chamber.

10. A refrigeration cycle device is provided with:

the multi-stage rotary compressor of any one of claims 1 to 9;

a radiator connected to a discharge portion of the multistage rotary compressor;

an expansion device connected to a downstream side of the radiator; and

and a heat absorber connected between a downstream side of the expansion device and an introduction portion of the multistage rotary compressor.